Essentially, any label, be it "professionally diagnosed" / "Self-diagnosed" / "undiagnosed" is just a simplification... none of them are adequate in the exploration of the human traits.
Diagnosis is just what the outside uses to describe what they feel to be "clinically significant".
If they feel someone is "different enough" then a diagnosis is made.
It's just a tool that bureaucratic society needs to properly "control" the situation of people being different. I think of it like the "minority" label. It's just pointless, except in the scope of how society chooses to deal with differences.
Any reasonable person who is actually searching for real self improvement would be able to seek it by becoming acquainted with the FACTS published by known experts, as well as the experiences of others, and would be able to leverage their own reason to avoid using traits/labels as excuses for stupid behavior. Instead of making excuses for exclusion or self-stagnation they would be able to learn and grow wiser about themselves.
I think the label self-diagnosed is particularly stupid, as stupid really as the idea of clinically diagnosed. If you have traits, you have traits. No one can tell you who you are but your own self.
Not all of us who have these traits had the opportunity to have good support while growing up. I'd imagine most coming here now who are undiagnosed but recognize the essential traits are seeking to learn from the community who have had that type of perspective, the kind of self-lucidity required to really learn effective strategies. We're just barely gaining that level of lucidity. It's likely we were misdiagnosed and harshly misunderstood throughout life to this point.